Sheared polymer blends and process for their preparation

ABSTRACT

A blend and a process for producing that blend in which a high ethylene content ethylene-propylene polymer and a lower ethylene content ethylene-propylene polymer are subjected to simultaneous blending and shearing to reduce their molecular weights and molecular weight distribution. The sheared blend of polymers can function as a shear stable dispersant viscosity index improver with improved lower temperature properties or the hydrocarbon base for multifunctional for viscosity index improvers, motor fuel additives or polymeric dispersants.

This is a continuation of application(s) Ser. No. 08/529,524, filed Sep. 18, 1995, now abandoned which is a continuation-in-part of Ser. No. 08/336,420 filed Nov. 9, 1994 now U.S. Pat. No. 5,451,636 which is a divisional of Ser. No. 08/100,303 filed Aug. 2, 1993, now U.S. Pat. No. 5,391,617.

INTRODUCTION

This invention relates to ethylene-propylene polymers and, more specifically, to blends of such polymers prepared by simultaneously blending and shearing the polymers to reduce their molecular weights and molecular weight distribution. The ethylene-propylene polymers of the present invention have unique properties which enable them to be processed in conventional plastic processing equipment.

BACKGROUND OF THE INVENTION

Ethylene-propylene polymers have long been known, and used for a variety of applications. For example, such copolymers, frequently referred to in the art as olefin copolymers or OCPs, have long been recognized as viscosity index improvers in engine lubricating oils. Such olefin copolymers have been derivatized to provide multifunctional viscosity index improvers additionally imparting dispersant, antioxidant and/or antiwear activity to the lubricating oil. The olefin copolymers, when prepared at very low molecular weights, are derivatized to function as dispersant polymers and motor fuel additives. In addition to such applications, olefin copolymers have also been widely used as impact modifiers for plastic compositions.

As used in lubricating oil compositions, ethylene-propylene polymers have the ability to provide a high thickening contribution to the lubricating oil composition with which the OCP is mixed to provide increases in the viscosity index of the overall composition. Thickening power is often defined as the difference in the kinematic viscosities of a dilute solution of an OCP mixed with oil and the diluent oil. For example, an oil solution containing from 1 to 2 percent of an OCP which provides a thickening power of 6 to 7 centistokes measured at 100° C. generally indicates acceptable viscosity index improvement performance.

For a given class of polymers, the higher the molecular weight, the higher is the viscosity of a lubricating oil containing the OCP. However, higher molecular weight polymers exhibit a greater tendency to break down under the shear and high temperature conditions normally found in engine operation, frequently resulting in the loss of viscosity. Accordingly, viscosity index improvement often depends on the balance between the thickening contribution of the OCP and its tendency to degrade, referred to as shear stability. Shear stability is typically defined as a percent viscosity breakdown on shear under a standard set of conditions. A value below 30 percent viscosity breakdown in an OCP is generally an indication that the viscosity index improver OCP is shear stable as that term is understood in the art.

Another important characteristic required for a viscosity index improver is viscosity at low temperatures, which relates to the ease of engine cranking during start-up in cold climates. An ideal viscosity index improver exhibits a negligible viscosity contribution at low temperatures while providing a large viscosity contribution at engine operating temperatures. At the same time, an ideal viscosity index improver exhibits a low tendency to degrade, and consequently a high shear stability under engine operating conditions.

Accordingly, in formulating lubricating oils to satisfy the varying conditions desired, it has generally been the practice to select those polymers which provide at the lowest cost the best overall balance of properties including viscosity at performance temperatures, shear stability and low temperature viscosity.

In the past, the art has employed as viscosity index improvers, solid amorphous ethylene-propylene polymers. When selecting ethylene-propylene polymers, a molecular weight was chosen so that the polymer would provide shear stable viscosity index improvement after the oil dispersion process. These solid ethylene-propylene polymers were generally sheared during the oil dispersion, solution process resulting in lower molecular weight ethylene-propylene polymers. Oil concentrates of these lower molecular weight ethylene-propylene polymers were utilized as viscosity index improver packages by oil formulators. The sheared ethylene-propylene polymers that dissolved in oil, if isolated or prepared neat, were no longer stable solids but would exhibit extreme cold flow properties or exist as viscous oils. Such ethylene-propylene polymer viscosity index improvers as used in the prior art typically exhibit a Reduced Solution Viscosity or RSV, measured on a 0.05 weight % solution of the polymer in decalin at 135° C., less than about 1.5 dl/g when they provide shear stable viscosity index improvement. Near that RSV limit, such ethylene-propylene polymers are difficult to recover and package using conventional rubber coagulation, recovery and packaging equipment.

Past efforts to handle such polymers as concentrated solutions in oil containing 5 to 20 percent by weight of the ethylene-propylene polymer viscosity index improver have met with limited success by reason of the disadvantages of requiring large amounts of oil in which the viscosity index improvers must be dispersed, and that in turn results in additional costs in transportation and, in some cases, additional tariffs by reason of the oil present even though the polymer is the component of interest.

The prior art has recognized the need to improve low temperature performance of such viscosity index improvers. For example, U.S. Pat. No. 4,507,515 describes blends of polymer compositions in which the major component has a low ethylene content and the minor component has a higher ethylene content, the minor component generally containing less than 10 percent by weight based on the weight of the blend. Similarly, U.S. Pat. No. 3,697,429 likewise describes the use of blends of high and low ethylene content polymers to achieve improvement in low temperature properties of a lubricating oil composition. One of the shortcomings of both prior art patents is that they describe handling the major and minor components solely as oil solutions.

In Canadian Patent No. 911792, there is disclosed a process for shearing high molecular weight polymers to produce a polymer having a desired molecular weight without altering the molecular weight distribution for use as a viscosity index improver. That Canadian patent does not, however, address the need for a shear stable polymer formed by shearing the polymer to reduce its molecular weight and its molecular weight distribution.

The present invention addresses the need to provide an oil-free polymer having the capability of functioning as a shear stable viscosity index improver and, additionally, the capability of being derivatized to function as a dispersant, antioxidant and/or antiwear agent when incorporated into lubricating oil or motor fuel. According to the concepts of the invention, the ethylene-propylene polymer of the invention is the product of a simultaneously blended and sheared blend containing a high ethylene content ethylene-propylene polymer and a lower ethylene content ethylene-propylene polymer. The composition of the present invention in which the two components are simultaneously blended and sheared can thus be used as a viscosity index improver exhibiting improved low temperature properties as compared to (a) either of the two components used in preparing the blend and (b) blends of the same two components prepared by other blending techniques. The blends of the present invention find use not only as multifunctional viscosity index improvers, polymeric dispersants and motor fuel additives, but can also be used to improve the impact strength of various plastics such as polyamides or nylon, polyesters, polyolefins and like thermoplastic and thermosetting compositions, or as a plasticizer/antiozonant for rubber/rubber blends, and as an additive for adhesive compositions.

It is accordingly an object of the present invention to provide an oil-free ethylene-propylene polymer blend which overcomes the shortcomings of the prior art.

It is a more specific object of the invention to provide an ethylene-propylene polymer blend and a method for its preparation which can be used to improve viscosity index of lubricating oil compositions as well as an impact modifier for plastic compositions in which the blend is subjected to simultaneous blending and shearing to reduce the molecular weight and the molecular weight distribution of each of the ethylene-propylene polymer components.

It is an object of the invention to provide a low molecular weight ethylene-propylene polymer blend that can be derivatized to provide dispersant properties to lubricating oil or function as a motor fuel additive.

It is a further object of the invention to provide an ethylene-propylene polymer blend that can be derivatized to provide a multifunctional viscosity index improver imparting dispersant, antioxidant and antiwear properties to lubricating compositions.

These and other objects and advantages of the present invention will appear more fully by way of the following description.

SUMMARY OF THE INVENTION

The concepts of the present invention reside in a blend and a process for producing that blend in which a high ethylene content ethylene-propylene polymer and a lower ethylene content ethylene-propylene polymer are subjected to simultaneous blending and shearing to yield a product that can be used directly as a viscosity index improver or derivatized to function as a polymeric dispersant, a multifunctional viscosity index improver or a motor fuel additive. It has been unexpectedly found that the sheared blend can function as a shear stable viscosity index improver with improved lower temperature properties. The blend can also be used in other applications, notably including as an impact modifier for plastics, component in thermosetting compositions, or a plasticizer/antiozonant for rubber/rubber blends.

In carrying out the simultaneous blending and shearing in accordance with the features of the present invention, the two ethylene-propylene components undergo shearing to reduce molecular weights and molecular weight distribution (MWD), resulting in an intimate admixture exhibiting increased viscosity at ambient temperatures.

DETAILED DESCRIPTION OF THE INVENTION

The ethylene-propylene polymers used in the practice of the present invention refer to and include ethylene-propylene copolymers or copolymers of ethylene and propylene with other alpha olefins, as well as copolymers formed by the interpolymerization of ethylene, alpha olefins and at least one other polyene monomer. Such polymers are themselves well known to those skilled in the art and are typically prepared by using conventional Ziegler-Natta polymerization techniques well known to those skilled in the art. Both types of polymers hereinafter collectively referred to as EP(D)M.

As will be appreciated by those skilled in the art, while propylene is the preferred monomer for copolymerization with ethylene and optionally a diene monomer, it will be understood that in place of propylene, use can be made of other alpha-olefins containing 4 to 12 carbon atoms. The use of such higher alpha-olefins in place of propylene are well known to those skilled in the art in Ziegler technology.

When using an interpolymer of ethylene, an alpha-olefin and a polyene monomer, use can be made of a variety of polyene monomers known to those skilled in the art containing two or more carbon-to-carbon double bonds containing 4 to 20 carbon atoms, including non-cyclic polyene monomers, monocyclic polyene monomers and polycyclic polyene monomers. Representative of such compounds include 1,4-hexadiene, dicyclopentadiene, bicyclco-(2,2,1)hepta-2,5-diene, commonly known as norbornadiene as well as the alkenyl norbornenes wherein the alkenyl group contains 1-20 carbon atoms and preferably 1-12 carbon atoms. Examples of some of the latter compounds includes 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, vinyl norbornene as well as alkyl norbornadienes.

Also included among the ethylene-propylene polymers used in the concepts of the present invention are those EPM and EPDM polymers which have been functionalized by means of a free radical graft reaction or a graft polymerization reaction. Such grafted polymers are themselves well known to those skilled in the art. Suitable graft monomers include unsaturated dicarboxylic acid anhydrides and their corresponding acids, preferably those having the general formula: ##STR1## wherein R is an alkyl group having 0 to 4 carbon atoms and Y is preferably hydrogen but may also be an organic group such as a branched or straight chain alkyl group, an anhydride, a ketone group, a heterocyclic group or other organic group containing 1-12 carbon atoms. In addition, Y can be a halogen such as chlorine, bromine or iodine. X can be OH or an alkoxy group wherein the alkyl group contains 1-8 carbon atoms. Preferred among those graft monomers are maleic anhydride, itaconic anhydride.

Also suitable as the graft monomer for functionalizing an EPM or EPDM interpolymer are the derivatives of olefinically unsaturated carboxylic monomers such as, acrylic or methacrylic acid, or their esters, graft monomers which are likewise known to those skilled in the art. Typically, acrylic and methacrylic acid derivative contain 4 to 16 carbon atoms. Preferred among the acrylic and methacrylic acid graft monomers are those having the structure: ##STR2## wherein R¹ is hydrogen or C₁ to C₄ alkyl (e.g., methyl, ethyl, etc.) and R² is selected from the group consisting of a C₁ to C₈ alkyl group, a keto functional alkyl group, an epoxy functional alkyl group, --NH₂ or --NR₂ where R can be H or C₁ to C₈ hydrocarbon and both R groups need not be the same. Particularly preferred among the group of acrylic or methacrylic graft monomers are glycidyl methacrylate, methylacrylate, methylmethacrylate, ethylmethacrylate and aminopropylmethacrylate, and acrylamide.

Another group of graft monomers which can be used to functionalize an EPM or EPDM interpolymer are vinyl amines containing 2 to 25 carbon atoms, and preferably heterocyclic vinyl amines. Such amines are themselves known as functionalizing graft monomers and include allylamines, N-vinylpyridines, N-vinylpyrrolidones, vinyl lactams, vinylcarbazoles, vinylimidazoles and vinylthiazoles as represented by 2-vinylpyridine, N-vinylpyrrolidone, vinyl caprolactam, 1-vinylimidazole, allylamine, 4-methyl-5-vinylthiazole and 9-vinylcarbazole. Such graft monomers are described in detail in U.S. Pat. No. 4,340,689, the disclosure of which is incorporated herein by reference.

As will be appreciated by those skilled in the art, the graft reaction as described above can be carried out on the ethylene-propylene polymers either before or after blending and shearing. It is possible to react either the high ethylene content ethylene-propylene polymer or the lower ethylene content ethylene-propylene polymer, or both of them, with the graft monomer under free radical conditions before simultaneously blending and shearing. Alternatively, it is also possible to react the graft monomer under free radical conditions as described with the ethylene-propylene polymer blends, that is after blending and shearing. In the latter case, the graft monomer randomly reacts with each of the two components of the blend.

In accordance with the practice of the invention, it is possible, and sometimes desirable, to further derivatize the grafted ethylene-propylene polymer blends of the invention by reaction with an organic compound capable of reaction with the functionality introduced by the grafted monomer to provide multifunctional viscosity improvers or polymeric dispersants by methods known to those skilled in the art.

Descriptions of suitable methods, graftable monomers, and reactive organic compounds for converting ethylene-propylene polymers into multifunctional viscosity improvers and polymeric dispersants are described in U.S. Pat. Nos. 4,340,689, 4,670,515, 4,863,623, 5,021,177, 5,035,819, 5,094,765, 5,094,766, 5,147,569, 5,112,508, 5,160,446, 5,162,086, 5,167,845, 5,182,041, 5,188,745, 5,200,100, 5,200,102, 5,238,588, 5,264,139, 5,264,140, 5,275,746, 5,374,364, 5,384,371, 5,409,623, 5,424,366, the disclosures of which are incorporated herein by reference.

Organic molecules useful for reacting with functionality grafted onto the ethylene-propylene polymer blends are categorized as possessing either one or more reactive groups from the class of primary amines, hydroxyls, and thiols, wherein the primary amine, hydroxyl, or thiol is the most reactive functionality in the organic molecule. Examples of classes of organic molecules useful for lubricating oil applications include alkylene polyamines, aryl polyamines, heterocyclic polyamines, or combinations thereof. Specific examples of alkylene polyamines include ethylene diamine, diethylene triamine, tetraethylene pentamine, N,N-dimethylaminopropyl amine, N-octadecyl-1,3 propane diamine, N-oleaylaminopropyl-1,3 propane diamine, dihexamethylene triamine.

Specific examples of aryl polyamines include N-phenyl-phenylene diamine, N-naphthyl-phenylene diamine, and substituted forms thereof as represented by the formula: ##STR3## in which Ar is an aromatic group, R' is H, --NH-aryl, --NH-ary alkyl, --NH-alkyl, or a branched or straight chain radical having 4-24 carbon atoms that can be alkyl, alkenyl, alkoxy, aryalkyl, hydroxyalkyl, aminoalkyl, R" is --NH₂, --NH(CH₂)_(n))_(m) NH₂, --CH₂ --(CH₂)_(n) --NH₂, -aryl-NH₂ in which n and m have a value from 1-10, and R'" is --H, alkyl, alkenyl, alkoxy, aralkyl, alkaryl having 4 to 24 carbon atoms and with the proviso that at least R' or R" must have a terminal NH₂.

Useful heterocyclic polyamines can be selected from the groups represented by the formula:

(a) an aminocarbazole ##STR4## in which R and R' represent hydrogen, or an alkyl, alkenyl, or alkoxy radical having 1 to 14 carbon atoms;

(b) an aminoindole ##STR5## in which R represents hydrogen or an alkyl radical having from 1 to 14 carbon atoms;

(c) an aminopyrrole ##STR6## in which R is a divalent alkylene radical having 2-6 carbon atoms and R' is hydrogen or an alkyl radical having 1 to 14 carbon atoms;

(d) an amino-indazolinone ##STR7## in which R is hydrogen or an alkyl radical having from 1-14 carbon atoms; (e) an aminoperimidine ##STR8## in which R represents hydrogen or an alkyl or alkoxyl radical having from 1 to 14 carbon atoms;

(f) an aminomercaptotriazole ##STR9## in which R can be absent or is a (C₁ -C₁₀) linear or branched hydrocarbon selected from the group consisting of alkyl, alkenyl, aryalkyl, or aryl;

(g) an aminomorpholine, an aminopiperazine, an aminopiperidine ##STR10## in which R is --CH₂ (CH₂)_(n) --NH₂ and n is a value of 0 to 10 and R' is H or R;

(h) an aminophenothiazine ##STR11## in which R' is --NH₂, ##STR12## and n has a value from 1-10, NH₂ -aryl-, NH₂ -arylalkyl-, R" is H, or a (C₁ -C₂₄) branched or straight chain alkyl, alkenyl, alkoxy, arylalkyl, hydroxy alkyl or amino alkyl radical;

(i) an aminopyridine, aminopyrazines, aminopyrimidines ##STR13## in which R represents hydrogen, aryl, alkyl, alkenyl, alkoxy, aralkyl, hydroxyalkyl, or aminoalkyl radical having 1 to 18 carbon atoms;

(j) an aminoimidizolidone ##STR14## in which R in each instance is the same or different and maybe H, branched or straight chain radical having 1 to 24 carbon atoms that can be alkyl, alkenyl, alkoxy, aralkyl, n has a value of 0-12, m has a value of 0 to 2, and X is either 0 or S;

(k) an aminothiadiazole, an aminothiothiadiazole ##STR15## in which R is hydrogen, or a (C₁ -C₁₀) branched or linear hydrocarbon selected from the group consisting of alkyl, alkenyl, aralkyl, alkaryl, hydroxy alkyl and amino alkyl, and R' is --NH₂, --CH₂ (CH₂)_(n) --NH₂ --CH₂ -aryl-NH₂ and n is a value of 0 to 10.

(1) an aminobenzotriazole ##STR16## in which R is --CH₂ --(CH₂)_(n) --NH₂ with n having a value of 0 to 10, R' is hydrogen or a (C₁ -C₁) branched or linear hydrocarbon selected from the group consisting of alkyl, alkenyl, alkoxy, aralkyl, alkaryl, hydroxy alkyl, and amino alkyl;

(m) an aminoimidazoline, an aminothiazoline ##STR17## in which R' is a linear, cyclic, heterocyclic or heteroaromatic group optionally containing one or more atoms of oxygen, nitrogen, sulfur or phosphorous, and R is hydrogen or R';

Useful heterocyclic thiols can be selected from the groups represented by the formulas:

a mercaptobenzothiazole, a mercaptobenzoimidazole ##STR18## in which R can be absent or is a (C₁ -C₁₀) linear or branched hydrocarbon selected from the group consisting of alkyl, alkenyl, aryl, arylalkyl, and R' can be hydrogen, R, an amino alkyl, a hydroxyalkyl wherein the alkyl group has 1 to 3 carbon atoms.

Very low molecular weight ethylene-propylene polymer blends of the present invention, Mn of 300 to 3500, find use as motor fuel additives when first grafted or thermally reacted with an organic unsaturated dibasic acid, acid anhydride or diester and the reaction product thereof is then reacted in a second step with a polyoxyalkylene diamine of the formula: ##STR19## in which R' represents hydrogen or an alkyl radical having from 1 to 2 carbon atoms and the backbone polyoxyalkylene radical consists of from about 5 to 65 weight percent of alkylene oxide and n has a value of from 5 to 200 to form an imide functional ethylene-propylene polymer. Methods to derivatize such ethylene-propylene polymers are described in the above-referenced patents and in U.S. Pat. Nos. 4,968,321 and 5,366,518.

As it will be appreciated by those skilled in the art, other vinyl monomers described in the prior art as suitable for functionalizing such EPM and EPDM interpolymers may likewise be used in the practice of the present invention. Examples of such further vinyl compounds are the vinyl silanes and vinylbenzyl halides as represented by vinyltrimethoxysilane, vinyldiethychlorosilane, vinylbenzylchloride and the like. Further descriptions of suitable silane graft monomers are described in U.S. Pat. No. 4,340,689, the disclosure of which is incorporated herein by reference.

As described above, the composition of the present invention prepared by simultaneously blending and shearing utilizes, as starting materials, two different ethylene-propylene polymers, one being characterized by low ethylene content and the other being characterized by a higher ethylene content. The ethylene-propylene polymers having the low ethylene content has a polymerized ethylene/propylene molar ratio in the range of 35/65 to 65/35, and preferably a molar ratio of 50/50 to 65/35. When incorporated into a blend for use as a solid shear stable viscosity index improver, the preferred ratio of ethylene to propylene is 50/50 to 60/40. When the ethylene-propylene polymer also includes a third polyene monomer, the amount of the polyene monomer generally ranges from about 0.1 to about 10 percent, and preferably 0.2 to 5 percent by weight based on the total weight of the polymer. When, however, use is made of a preferred polyene monomer, vinyl norbornene, the most preferred range is from 0.1 to 1 percent by weight. When the ethylene-propylene monomer has been grafted with a graft monomer to functionalize the ethylene-propylene polymer, either with or without a polyene termonomer, use is preferably made of 0.1 to 6 percent by weight of the graft monomer, depending somewhat on the application of the final graft polymer.

The number average molecular weight of the low ethylene content ethylene-propylene polymer generally ranges from about 20,000 to about 150,000 as measured by GPC in trichlorobenzenes at 135° C. In the preferred practice of the present invention, the low ethylene content ethylene-propylene polymer has a molecular weight distribution within the range of about 1.5 to 7. As is well understood by those skilled in the art, the molecular weight distribution, often referred to as M_(w) /M_(n) is determined by gel permeation chromatography according to well understood techniques, as more specifically described hereinafter.

The second component used in preparing the composition of the present invention is one having a higher ethylene content. In the preferred practice of the invention, the high ethylene content ethylene-propylene polymer has a polymerized ethylene/propylene molar ratio ranging from about 65/35 to about 85/15. When incorporated into a blend for use as a shear stable viscosity index improver, the preferred ratio of ethylene to propylene is 70/30 to 80/20. In general the same quantities of polyene monomers and graft monomers are used in the preparation of the second, high ethylene content ethylene-propylene polymer as described above. It will be understood, however, that the composition of the higher ethylene content polymer need not employ the same combination of monomers as is used in the low ethylene content ethylene-propylene polymer. In the preferred practice of the invention, the number average molecular weight of the higher ethylene content ethylene-propylene polymer likewise ranges from about 20,000 to about 150,000 as measured by GPC in trichlorobenzene as described above. The molecular weight distribution of the high ethylene content ethylene-propylene polymer falls within the same range of about 1.5 to 7.

The low ethylene content ethylene-propylene polymer is, as will be understood by those skilled in the art, a random copolymer which is essentially amorphous. As is well recognized by those skilled in the art, the degree of crystallinity of a polymer is most often determined by Differential Scanning Calorimetry, or DSC. By using that standard, the low ethylene content ethylene-propylene polymer typically has less than 3 percent by weight crystallinity as determined by DSC. The higher ethylene content ethylene-propylene polymer, on the other hand, has a higher degree of crystallinity, ranging up to about 25 percent as determined by DSC. Typically, the higher ethylene content polymer has a degree of crystallinity ranging from about 6 to 20 percent as determined by DSC.

The two components, when simultaneously blended and sheared according to the concepts of the present invention, undergo a chemical reaction by reason of the heat and energy of shearing supplied to the blend. That reaction results in a reduction in the molecular weight of the blend as well as a reduction in the molecular weight distribution of the blend. In general, good results are obtained when the number average molecular weight of the blend is controlled within the range of about 300 to about 100,000. The preferred number average molecular weight of the blend for use as a solid shear stable viscosity index improver is 1,000 to 75,000. For use as multifunctional viscosity index improvers, blends with Mn of 5,000 to 75,000 are preferred and for use as motor fuel additives or polymeric dispersants, a Mn of 300 to 5,000 is typically preferred. The molecular weight distribution of the composition after simultaneous blending and shearing is generally within the range of about 1.2 to about 5. The desired blend molecular weight and molecular weight distribution is determined by its particular end use.

The relative proportions of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer depend, to some extent, on the application of the composition of the invention. In general, good results have been obtained when the lower ethylene content component to the higher ethylene content component has a weight ratio of 80/20 to about 50/50, and preferably 70/30 to about 60/40.

In carrying out the simultaneous blending and shearing in accordance with the concepts of the present invention, the two ethylene-propylene polymer components are contacted with each other under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weights and molecular weight distributions of those two components to a level desirable for the particular end use application. That operation can be carried out in a number of known types of plastic processing equipment such as single or twin screw extruders, a Banbury, as well as other mixers that have the capability of effecting the mechanical work on the components so that in the presence of an elevated temperature, reduction in the molecular weights and molecular weight distributions to the desired level is effected. The conditions of temperature, feed rate, and screw speed are determined, in part, by the molecular weight reductions desired as well as the process time desired, given the processing economics. In general, depending somewhat on the compositions of the components, processing temperatures within the range of 150° to 400° C. can be used, and preferably 175° to 320° C. The preferred embodiment makes use of a twin screw extruder.

The ethylene-propylene polymer components are generally conveniently in the form of ground or pelletized rubber which are supplied simultaneously to the extruder in which they are blended and simultaneously sheared. As will be appreciated by those skilled in the art, the components can also be supplied as either a pre-mixed bale or a pre-mixed friable chopped agglomerate form.

A nitrogen feed is maintained at the feed section of the extruder to minimize the introduction of air.

The ground rubber bales are fed to the twin screw extruder or other mixer along with 0.1 to 2 weight percent based on the total weight of blend polymers of an antioxidant to prevent excessive oxidation of the polymer blend during processing and storage. Choice of an antioxidant depends on the processing temperatures in the mixer as well as end use application.

The blended and sheared hot melt can generally be formed into pellets by a variety of process methods commonly practiced in the art of plastics processing. These included underwater pelletization, ribbon or strand pelletization or conveyor belt cooling. When the strength of the hot melt is inadequate to form into strands, the preferred method is underwater pelletization. Temperatures during pelletization should not exceed 30° C. Optionally, a surfactant can be added to the cooling water during pelletization to prevent pellet agglomeration.

The water mixture of blended and sheared pellets can be conveyed to a dryer such as a centrifugal drier for removal of water. Pellets can be collected in a box or plastic bag at any volume for storage and shipment. Under some conditions of storage and/or shipment at ambient conditions, pellets may tend to agglomerate and stick together. These can be readily separated by mild mechanical methods to provide high surface area pellets for easy and quick dissolution into oil or blending with other materials such as rubbers and plastics.

Polymers of the instant invention having an RSV above 0.5 dl/g can generally be processed using underwater pelletization. Strand chopping is difficult because the strands break easily, leading to interruptions in production. Below 0.5 RSV the polymer is somewhat soft until it cools and sets. For this type of product, a cooled belt recovery system is preferred. This is a revolving stainless steel belt that is sprayed with a cooling solution on the underside of the belt. The surface of the belt can be treated with a release agent. Depending on the consistency of the product, it can be removed from the belt by prilling or by scraping off with a knife edge.

Optionally, as end use permits, a partitioning agent, such as talc, metal stearates and polyolefin dusts can be applied when conveying the pellets to packaging equipment to prevent agglomeration during storage.

It has been unexpectedly found in the practice of the present invention that the properties of the composition, after simultaneously blending and shearing, differ markedly with respect to either of the two components employed in preparing the blend and also differ markedly from the properties of blends prepared by other techniques. Without limiting the present invention as to theory, it is believed that it is essential in carrying out the present invention that the blending of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer be effective such that the blending and shearing occurs simultaneously with each of the two components in the presence of each other. It has been found, for example, that different properties are obtained if the two components are separately sheared to reduce the molecular weights and molecular weight distributions and thereafter blended together. Indeed, it has even been found that the properties of the composition produced by simultaneously blending and shearing of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer differ in significant respects from blends prepared by controlling, during the polymerization reaction itself, the molecular weights of each component so that each has a molecular weight and a molecular weight distribution like that of the final blend, followed by blending the two polymers.

That effect may be illustrated by FIG. 1 which is a plot of complex viscosity as a function temperature as measured by a dynamic mechanical analyzer. As will be appreciated by those skilled in the art, it is desirable to overcome the prior art problems associated with polymer recovery, packing, and storage to maintain high levels of viscosity and/or crystallinity of the blend at ambient temperatures. The plot of FIG. 1 Curve I shows an embodiment of the present invention which is prepared by simultaneously blending and shearing a high ethylene content ethylene EPDM having a number average molecular weight of about 52,000 and a low ethylene content EPDM having a number average molecular weight of about 87,000 to a combined number average molecular weight of 35,000. As can be seen on the plot of FIG. 1, the complex viscosity rapidly increases from a relatively low level with decreasing temperature.

One of the unexpected features of the present invention may be seen by comparing Curve I, the composition of the present invention, with Curve II, for a more crystalline ethylene-propylene polymer identified as "A", a high ethylene content polymer having a number average molecular weight of about 43,000 which has not undergone any shearing. As can be seen from FIG. 1, the composition of the present invention which measures 7 weight percent crystallinity by DSC, Curve I, has a complex viscosity as a function of temperature which is very similar to that of ethylene-propylene polymer A, a polymer measuring 22 weight percent crystallinity by DSC and which is wholly unsuitable for use as a viscosity index improver because it lacks cold storage stability. When using such relatively high crystalline ethylene-propylene polymers as polymer A as a lubricating oil additive, there is a tendency for visible gel formation in the oil solution on storage. The composition of the present invention, because essentially amorphous and crystalline polymers have been intimately blended and sheared simultaneously, exhibits little or no tendency to form gels as does polymer A, while providing essentially comparable viscosity index improver characteristics with increasing temperatures.

FIG. 1 also demonstrates other wholly unexpected properties of the composition of the present invention. The same EPDM polymers used in preparing the composition of the present invention were also separately sheared, solution blended and isolated to generate Curve III. A comparison of that curve with Curve I, illustrating the composition of the present invention, shows that the complex viscosity as a function of temperature of the composition of the present invention is far superior to that of the same starting polymers which were separately sheared and then blended together. That comparison thus illustrates the importance of conducting the shearing operation in the presence of each of the two components used in making the composition of this invention.

That same effect is further demonstrated by Curve IV, a composition prepared by solution blending two EPM polymers, A and B both prepared by conventional polymerization, so that their molecular weights would be comparable to sheared polymer C (E) and sheared polymer D (F). The number average molecular weight of the blend of A plus B is approximately 38,000, essentially the same as the number average molecular weight of the composition of the present invention depicted in Curve I, the latter having a number average molecular weight of about 35,000. Curve IV resembles Curve III and further distinguishes the composition of the present invention over those obviously prepared by blending.

Compositions of the present invention, obtained by simultaneously blending and shearing in conventional plastic processing equipment provides far superior complex viscosity as a function of temperature as compared to blends at a similar molecular weight where the polymers were directly polymerized or those which were separately sheared then blended. Without limiting the invention as to theory, it is believed that the process of simultaneously blending and shearing provides an admixture which develops imperfect crystallites during processing and storage but when dissolved in solution behaves more like an amorphous conventional viscosity index improver. This phenomena of increased complex viscosity as a function of temperature is not an artifact of the specific ratio of the two polymers as can be seen in FIG. 2 where Curve VII represents a 50/50 blend, Curve VIII represents a 70/30 blend, and Curve IX a 60/40 blend of polymer D and C prepared by the process of this invention. Curves V and VI represent sheared polymer D (F) and sheared C (E) each sheared independently. Curves VII, VIII, and IX like Curve I, FIG. 1 (a 65/35 blend) show a complex viscosity at ambient temperatures like that of the higher crystalline ethylene-propylene polymers. Polymer E (Curve VI) measures a DSC crystallinity of 15 weight percent.

The following examples are provided to illustrate the inventions.

Materials used to demonstrate the concepts of this invention include the following:

Polymer A: an ethylene-propylene copolymer (EPM) containing 76-80 mole % ethylene with a Mn of 43,000, a MWD of 1.8, a RSV of 1.3, and a DSC crystallinity of 22 weight %, prepared by conventional polymerization.

Polymer B: an amorphous EPM containing 59 mole % ethylene with a Mn of 37,000, a MWD of 2.1, a RSV of 1.1, and no DSC crystallinity prepared by conventional polymerization.

Polymer C: an EPDM containing 78 mole % ethylene, 0.2-0.4 weight % vinyl norbornene, a Mn of 52,000, MWD of 2.9, a RSV of 2.6, and DSC crystallinity of 13.5 weight % prepared by conventional polymerization.

Polymer D: an amorphous EPDM containing 59 mole % ethylene, 0.5-0.7 weight % vinyl norbornene, a Mn of 87,000 MWD of 3.8, a RSV of 2.0, and DSC crystallinity of 0.5 weight % prepared by conventional polymerization.

Polymer E: an EPDM prepared by shearing Polymer C to a RSV of 1.3, GPC measured Mn of 34,000, a MWD of 1.9, DSC measured 15.3 weight % crystallinity, sheared by procedure of Example 1.

Polymer F: an EPDM prepared by shearing Polymer D to an RSV of 1.0, GPC measured a Mn of 27,000, a MWD of 2.8, DSC measured 1.0 weight % crystallinity, Sheared by procedure of Example 1.

Polymer G: an amorphous EPM containing 56 mole % ethylene, Mn of 54,000, MWD of 2.3, an RSV of 1.7, prepared by conventional polymerization and solution grafted with 1.2 weight % N-vinylpyrrolidone.

The following characterization and tests were conducted on the ethylene-propylene polymers, their blends, and oil concentrates of the blends:

Crystallinity: The weight percent crystallinity was calculated from thermograms obtained by cooling conditioned melted samples over the range 180° C. to -80° C. on a Perkin-Elmer DSC-7 Differential Scanning Calorimeter.

Gel Permeation Chromatograph: Number Average Molecular Weight, Mn, and Molecular Weight Distribution was determined on polymer samples dissolved in trichlorobenzene using a Waters 150C. ALC/GPC operated at 135° C. using a universal calibration curve based on polystyrene standards ranging in molecular weight from 3000 to 3,000,000.

Kinematic Viscosity: Measured according to ASTM-D445. The Thickening Power (TP) is the difference in centistokes (cSt) between the kinematic viscosities of the dilute solution of the VI improver and the diluent oil, measured at 100° C.

Shear Stability Index: Measured according to ASTM-D3945(A) Shear Stability Index (SSI) is determined as ##EQU1## Where Vbs and Vas are defined as the viscosities of polymer solution before and after shearing, respectively.

TP is defined as thickening power which is determined by the difference between Vbs and the viscosity of the solvent.

The (Vbs-Vas) is viscosity loss determined according to the ASTM Method D-3945 (Proc. A).

Bench Dispersancy: A sample VI-improver being tested is blended into a formulated oil which does not contain any dispersant to make a 10 weight percent solution of the VI improver in the formulated oil. This oil solution is then tested for dispersance in the Bench Dispersancy Test. In the Bench Dispersancy Test, the dispersancy of the experimental oil is compared to that of three reference oil standards which give excellent, good, and fair results in the test. The numerical value of a test result decreases with an increase in dispersant activity. A value above 150 indicates that the sample provides no dispersancy.

Cold Storage Stability (CSS): The cold storage behavior of a motor oil containing the VI-Improvers being tested was determined by utilizing the ultra low temperature environmental chamber (Thermotron S-AC). This test allows for the determination of the stability of the formulation under cold temperature conditions. An 18-hour cold temperature cycle was employed with the temperature ranging between -60° and 4° F. The samples were examined at 10° F., after eight weeks of storage under the noted conditions. Assessment of excellent, good, poor, bad made upon visual appearance of the solution.

Pour Point (PP): Measured according to ASTM-D97.

Cold Cranking Simulator (CCS: Measured according to ASTM-D2602 (at -25° C).

Mini-Rotoviscometer (MRV): Measured according to ASTM-D3829.

Comparative Example 1.

A blend of 65 weight % Polymer B and 35 weight % Polymer A was prepared by dissolving 65 g of B and 35 g of A in two liters of hexane. The solution was stirred overnight, then coagulated with excess isopropanol. The blend was filtered, sprayed with a solution 0.1 wt. % solution of Irganox 1076 in toluene then dried in a vacuum oven at 50° C. overnight. The recovered blend measured a Mn of 38,000, a MWD of 1.9 and a DSC crystallinity of 6.4 weight %.

Comparative Example 2.

A blend of 65 weight % Polymer F and 35 weight % Polymer E was prepared according to the procedure of Comparative Example 1. The recovered blend measured Mn of 32,000, a MWD of 2.5 and a DSC crystallinity of 7.4 weight percent.

EXAMPLE 1

Preparation of Blends at Different Ratios By Use of an Extruder to Simultaneously Blend and Shear Polymers D and C.

Polymers C and D were independently chopped into 1/4 inch granules and fed into a Werner & Pfleiderer ZSK 30 co-rotating twin screw extruder having a length to diameter ratio (L/D) of 42. Feed rates of the polymers were controlled to yield the ratio desired. Combined feed rates of 10-20 pounds per hour were used.

The temperature profile of the extruder was maintain over the six zones in the ranges: (1) 175°-200° C., (2) 230°-290° C., (3) 250°-320° C., (4) 250°-320° C., (5) 150°-200° C., and (6) 150°-200° C. This resulted in an average melt temperature of 180°-350°C., with a torque at 45-75 for a screw speed of 200 ppm. Sheared products having the same blend ratio but different RSVs were obtained by varying the extruder barrel temperature profile over the ranges described below. The sheared melt was formed into strands and cooled in a water bath, then pelletized. Wet pellets were air oven dried at 60°-70° C.

Blends were prepared at four different ratios of Polymers C and D at different barrel temperatures to vary the final blend molecular weight as measured by RSV. These are compared in Table I against comparative Polymers E and F, prepared by shearing each separately using the above procedure.

                  TABLE I                                                          ______________________________________                                                       Avg.                                                                   D/C     Barrel     Sheared                                               1-#   Ratio   Temp, °C.                                                                          RSV   Comments                                        ______________________________________                                         1     (100/0).sup.a                                                                          227        1.00  Comparative Polymer F                                                          (Sheared Polymer D)                             2     70/30   235        1.0                                                   3     70/30   212        1.2                                                   4     70/30   208        1.2                                                   5     65/35   226        0.9                                                   6     65/35   217        1.1                                                   7     65/35   218        1.2                                                   8     65/35   216        1.3                                                   9     60/40   231        0.9                                                   10    60/40   224        1.0                                                   11    60/40   215        1.1                                                   12    60/40   207        1.2                                                   13    50/50   219        1.2                                                   14    (0/100).sup.a                                                                          257        1.3   Comparative Polymer E                                                          (Sheared Polymer C)                             ______________________________________                                          .sup.a See comments.                                                     

EXAMPLE 2

Preparation of Oil Solutions and Tests as a Viscosity Improver

The polymers and polymer blends prepared in Example 1 and 2 were dissolved in a solvent neutral oil having an SUS at 100° F. of 100 by heating at 212°-320° F. under nitrogen in a glass reactor with mechanical stirring. The concentrate was then diluted with a pour depressed solvent neutral oil having an SUS 100° F. of 130 to form an oil solution having a kinematic viscosity of about 11.5 cSt. The oil solutions were tested according to ASTM methods as described above. The results are summarized in Table II.

                  TABLE II                                                         ______________________________________                                                      TP     SSI   CCS  MRV                                             2-#  RSV     (cst)  (%)   (cP) (cP)    PP   CSS.sup.1                          ______________________________________                                         1    1.00    6.8    24    3950 32,850  -36  Good                               2    1.0     6.6    22    3650 16,200  -30  Good                               3    1.2     6.4    22    3650 16,100  -30  Good                               4    1.2     6.5    23    3600 14,700  -30  Good                               5    0.9     6.6    16    3800 15,100  -30  Good                               6    1.1     6.5    22    3500 20,500  -30  Good                               7    1.2     6.5    27    3550 13,800  -33  Good                               8    1.3     6.4    30    3300 14,200  -33  Good                               9    0.9     6.5    18    3700 14,300  -30  Good                               10   1.0     6.6    21    3350 15,600  -30  Good                               11   1.1     6.6    26    3450 14,800  -33  Good                               12   1.2     6.8    30    3450 15,000  -30  Good                               13   1.2     6.5    22    3450 11,200  -30  Good                               14   1.3     6.4    20    3000 16,700  -18  Bad                                ______________________________________                                          .sup.1 Good means no gel formation on storage at low temperature. Bad          means gel formed during storage at low temperature after 2 weeks.        

EXAMPLE 3

Simultaneously Blending and Shearing Varying Extruder Conditions

Blend of 65 weight % D and 35 weight % C were prepared on a Werner & Pfleiderer ZSK-58 counter rotating twin screw extruder to examine the effect of screw speed and design on blend molecular weight, measured as a RSV, and oil solution properties, Thickening Power and Shear Stability Index. The following procedure was followed.

Polymers C and D were independently chopped into 1/4 inch granules and charged separately to two loss weight feeders for metering into the extruder. Feed rates of the polymers were controlled to yield the ratio desired for end use properties. Combined feed rates of 100 to 150 kg per hour were used. Extruder L/D was varied over the range 24-45. Nitrogen was also fed to the feed section to minimize the introduction of air into the extruder. An additional feed of 0.2 weight % based on the total feed rate of C and D of Weston 618F1 was metered to the feed section of the extruder with a volumetric screw feeder.

The temperature of the extruder was maintained to produce an average melt temperature of 230°-314° C. Screw speed was varied over the range 180 to 400 RPM. Venting of the extruder was accomplished through a vent stuffer so that volatile material could be removed and foaming of the melt avoided. Melt pelletization process was employed using water temperature of 10° C. to 30° C. Wet pellets were charged to a centrifugal drier operated at ambient temperature.

The procedure of Example 2 was followed for preparation of the oil solutions. Results are summarized in Table III.

                  TABLE III                                                        ______________________________________                                             Com-                                                                           bined                 Avg.                                                     Feed                  Barrel                                                   Rate    Extruder      Temp. Screw      TP   SSI                            3-# kg/hr   L/D      RPM  °C.                                                                           Design.sup.a                                                                         RSV  cSt  (%)                            ______________________________________                                         1   100     24       200  233   1     1.7  14   42                             2   100     24       300  259   1     1.1  7.6  19                             3   100     24       400  230   1     1.6  11.7 37                             4   150     45       300  275   2     1.1  7.1  18                             5   120     45       210  314   2     1.2  8.3  24                             6   140     45       300  296   2     1.1  6.6  21                             7   120     32       180  310   3     1.1  6.8  23                             ______________________________________                                          .sup.a 1 provides mild shearing; 2 provides intermediate shearing; 3           provides intense shearing.                                               

These examples demonstrate that the feed blend RSV can be significantly decreased (RSV of combined feed to the extruder was 2.2) to yield a blend with target properties for use as a viscosity index improver, regardless of screw design by optimizing the barrel temperature and screw speed. Examples 3-1 and 3-3 did not reach a reduction in molecular weight adequate to achieve the desired SSI of 23%.

EXAMPLE 4

Blends were prepared according to the procedure of Example 1 of Polymer G, a derivatized ethylene-propylene copolymer typically referred to as a DOCP when used as a viscosity index improver, and Polymer C. Blends were prepared at 80/20, 60/40 and 50/50 weight ratio of Polymer G to Polymer C and tested as a viscosity index improver in comparison with Polymer G alone. Results are summarized in Table IV.

                  TABLE IV                                                         ______________________________________                                                Blend    Blend  TP      SSI  Bench                                      4-#    Ratio    RSV    (cSt)   (%)  Dispersancy                                ______________________________________                                         4-1    60/40    1.2    6.6     26   110                                        4-2    50/50    1.1    6.7     15   150                                        4-3    80/20    1.1    6.6     21    80                                        4-4    100/0    0.9    6.8     20    65                                        ______________________________________                                    

EXAMPLE 5

Polymer Blend Sheared to Very Low Molecular Weight

Polymers C and D were independently chopped and fed in a ratio of 40/60 to the W&P ZSK-30 extruder as described in Example 1. A nitrogen purge was added at the feed inlet. Rubber feed rate was 5 lbs/hour. Screw speed was 100 rpm. Temperatures for the zones were: 105° C. (zone 1), 160° C. (zone 2), 225° C. (zone 3), 365° C. (zone 4) and 400° C. (zones 5-6). The melt temperature was 410° C. Torque was 85%. The product exiting the extruder was spread out in a thin sheet on a steel belt cooler that was cooled by means of refrigerated ethylene glycol/water mixture. As the belt turned, the product was scraped off the edge by a blade cutter. The scraped polymer was collected in a pail set below the blade edge. The product had a measured RSV of 0.20 dl/g. This corresponds to a number average molecular weight of about 4000. The polymer was dissolved in hot SNO 100 oil to give a final composition of 60 weight percent polymer in oil, which exhibited a kinematic viscosity of 1500 cSt at 100° C. A diluted oil solution, prepared as described in Example 2, exhibited a thickening power of 6.0 cSt and an SSI of 5%. The product is useful as a viscosity modifier for gear oils. It can also be derivatized and converted into an ashless dispersant for motor oils.

EXAMPLE 6

Polymer Blend Sheared to Very Low Molecular Weight

Polymers C and D were independently chopped and fed in a ratio of 40/60 to the W&P ZSK-30 extruder as described in Example 1. A nitrogen purge was added at the feed inlet. Rubber feed rate was 5 lbs/hour. Screw speed was 100 rpm. Temperatures for the zones were: 1500° C. (zone 1), 160° C. (zone 2), 225° C. (zone 3), 365° C. (zone 4) and 400° C. (zones 5-6). The melt temperature was 410° C. Torque was 85%. The polymer exiting the extruder had a measured RSV of 0.10 dl/g. This corresponds to a number average molecular weight of about 2000. The polymer blend exiting the extruder is collected by the method described in Example 5.

EXAMPLE 7

Polymer blend from Example 3 (-6) is dissolved in dry hexane at a concentration of 30 weight percent in an agitated stainless steel reactor. The reactor is heated to 155° C. Maleic anhydride (MA) dissolved in toluene is added under pressure to the reactor at a weight ratio 0.02 kg/kg of Polymer blend. After allowing for mixing of the graft monomer, dicumyl peroxide is pressured into the reactor at a weight ratio 0.5 gm peroxide per gm of graft monomer. The reactor temperature is held at 150°-160° C. with agitation for 60 mins. The hexane and toluene are removed under vacuum and the residual grafted polymer is titrated to contain 0.8 wt % maleic anhydride groups.

EXAMPLE 8

MA grafted polymer blend from Example 7 is dissolved in SNO-100 oil at a concentration of 13 weight percent in a reactor under nitrogen equipped with agitation and a thermocouple. The oil solution is heated to 160° C. and Sulfonic L-24-7, 0.08 g/g of polymer blend, is added along with a di(aminopropyl)phenothiazine (APTZ), at a ratio of 1.0 mole APTZ per mole MA functionality. The reaction mixture is heated at 180° C. for 6 hours under nitrogen. The solution is cooled to 80° C. and filtered through diatomaceous earth. The product as a 13% by weight concentrate in SNO-100 has a kinematic viscosity (100° C.) of 1200 Cst and a DIN SSI of 22 as measured on the standard oil dilution. The product is useful as a multifunctional viscosity index improver imparting dispersancy and antioxidant properties to the lubricating oil.

EXAMPLE 9A

Polymer blend from Example 5 is grafted with maleic anhydride according to the procedure of Example 7 except that the graft solids are 70 wt % and the MA charge is 3.0 wt % based on polymer blend. The isolated polymer has 2.5 wt % MA groups. The purified polymer is then dissolved in SNO-100 at 160° C. under nitrogen to provide a concentration of 50% by weight. N-phenyl-p-phenylenediamine, 1 mole per mole MA functionality, is added and the mixture is heated at 160° C. with agitation for 3 hours. The temperature is then lowered to 80° C. and the solution filtered through Celite. The derivatized polymer blend is useful as a dispersant/antioxidant additive when incorporated into a dispersant-inhibitor package with the lubricating oil.

EXAMPLE 9B

The MA grafted polymer blend as prepared above is reacted with tetraethylene pentamine in SNO-100 to provide a dispersant polymer concentrate.

EXAMPLE 9C

The MA grafted polymer blend as prepared above is reacted with 4-(aminomethyl)piperidine in SNO-100 to provide a dispersant polymer concentrate.

EXAMPLE 9D

The MA grafted polymer blend as prepared above is reacted with 4-(2-aminoethyl)morpholine to provide a dispersant polymer concentrate.

EXAMPLE 10

Polymer Blend from Example 6 is grafted with maleic anhydride according to the procedure of Example 7 to provide a 0.1 RSV polymer blend with 1 mole MA per polymer molecule. This anhydride grafted polymer is then reacted with a random backbone polyoxyalkylene diamine (prepared according to U.S. Pat. No. 5,366,518) containing 30 weight percent ethylene oxide at a ratio of 2 moles anhydride graft polymer per mole diamine in toluene. The reaction mixture is slowly heated to 150° C. under a nitrogen purge to remove water over a period of 8 hours. The solution is cooled to 80° C., filtered, and the solvent removed under vacuum. The polymer blend derivatized as a bisimide is mixed in a blending package for formulated motor fuel compositions such as taught in the above referenced U.S. patent. 

What is claimed is:
 1. An ethylene-propylene polymer blend having a number average molecular weight within the range of about 300 to about 5,000 and a molecular weight distribution within the range of about 1.5 to about 5 prepared by the process of simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50.
 2. A lubricating oil concentrate comprising a lubricating oil and the polymer blend of claim
 1. 3. A lubricating oil composition comprising a lubricating oil and the polymer blend of claim
 1. 4. A composition as defined in claim 3 wherein the composition includes a lubricating oil additive.
 5. A polymer blend as defined in claim 1 wherein the low ethylene content ethylene-propylene polymer contains less than 3 percent by weight crystallinity and the higher ethylene content ethylene-propylene polymer has a higher degree of crystallinity of no greater than 25 percent.
 6. A polymer blend as defined in claim 1 wherein at least one of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer includes a polyene monomer copolymerized therewith containing two or more carbon to carbon double bonds and containing 4-20 carbon atoms.
 7. A polymer blend as defined in claim 6 wherein the polyene is selected from the group consisting of non-cyclic polyene monomers, monocyclic polyene monomers and polycyclic polyene monomers.
 8. A polymer blend as defined in claim 1 wherein at least one of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer has been functionalized by means of a graft polymerization using a graft monomer.
 9. A polymer blend as defined in claim 1 wherein the polymer blend is further functionalized by graft polymerization using a graft monomer.
 10. A polymer blend as defined in claims 8 or 9 wherein the graft polymerization utilizes a graft monomer selected from the group consisting of unsaturated dicarboxylic acid anhydrides, their esters and their corresponding acids.
 11. A polymer blend as defined in claims 8 or 9 wherein the graft polymerization is carried out using a graft monomer in the form of a derivative in the form of an acrylic or methacrylic acid containing 4 to 16 carbon atoms.
 12. A polymer blend as defined in claims 8 or 9 wherein the polymer blend has been derivatized by reaction with a derivatizing compound containing one or more reactive groups selected from the group consisting of primary amines, hydroxyls and thiols.
 13. A polymer blend as defined in claim 12 wherein the derivatizing compound is selected from the group consisting of alkylene polyamines, aryl polyamines, heterocyclic polyamines and combinations thereof.
 14. A polymer blend as defined in claim 1 wherein both the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer have been functionalized by grafting.
 15. A derivatized ethylene-propylene polymer blend having a number average molecular weight within the range of about 300 to about 5,000 and a molecular weight distribution within the range of about 1.5 to about 5 prepared by the steps of simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, reacting the polymer with a graft monomer to form a functionalized blend, and further reacting the functionalized blend with a reactive organic compound containing one or more reactive groups selected from the group consisting of primary amines, hydroxyls and thiols.
 16. A polymer blend as defined in claim 15 wherein the reactive organic compound is selected from the group consisting of alkylene polyamines, aryl polyamines, heterocyclic polyamines and combinations thereof.
 17. A polymer blend as defined in claim 15 wherein the reactive organic compound is an aryl polyamine selected from the group consisting of N-phenyl-phenylene diamines, N-naphthylphenylene diamines and substituted derivatives thereof.
 18. A polymer blend as defined in claim 15 wherein the reactive organic compound is a heterocyclic polyamine selected from the group consisting of aminocarbazoles, aminoindoles, aminopyrroles, amino-indazolinones, aminoperimidines, aminomercaptotriazoles, aminomorpholines, aminopiperazines, aminopiperidines, aminophenothiazines, aminopyridines, aminopyrazines, aminopyrimidines, aminoimidizolidones, aminothiadiazoles, aminothiothiadiazoles, aminobenzotriazoles, aminoimidazoline and aminothiazolines.
 19. A polymer blend as defined in claim 15 wherein the reactive organic compound is selected from the group consisting of a mercaptothiazole, and a mercaptobenzoimidazole.
 20. A polymer blend as defined in claim 15 wherein the graft monomer is maleic anhydride and the reactive organic compound is a primary amine.
 21. A polymer blend as defined in claim 15 wherein the graft monomer is selected from the group consisting of unsaturated dicarboxylic acid anhydrides, their esters, their corresponding acids, and an acrylic acid containing 4 to 16 carbon atoms and a methacrylic acid containing 4 to 16 carbon atoms.
 22. A process for producing an ethylenepropylene polymer blend comprising simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, with the blending and shearing being carried out such that the polymer blend has a number average molecular weight within the range of about 300 to about
 5000. 23. A process as defined in claim 22 wherein the low ethylene content ethylene-propylene polymer contains less than 3 percent by weight crystallinity.
 24. A process as defined in claim 22 wherein the higher ethylene content ethylene-propylene polymer has a degree of crystallinity of no greater than 25 percent.
 25. A process as defined in claim 22 wherein at least one of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer includes a polyene monomer copolymerized therewith containing two or more carbon to carbon double bonds and containing 4-20 carbon atoms.
 26. A process as defined in claim 25 wherein the polyene is selected from the group consisting of non-cyclic polyene monomers, monocyclic polyene monomers and polycyclic polyene monomers.
 27. A process as defined in claim 25 wherein the polyene monomer is selected from the group consisting of 1,4-hexadiene, dicyclopentadiene, norbornadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, vinyl norbornene and the alkyl norbornadienes.
 28. A process as defined in claim 29 wherein the polyene is present within the range of about 0.1 to about 10 percent based on the total weight of the polymer.
 29. A process as defined in claim 22 wherein at least one of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer has been functionalized by means of a graft polymerization using a graft monomer.
 30. A process as defined in claim 29 wherein the graft monomer is selected from the group consisting of unsaturated dicarboxylic acid anhydrides and their corresponding acids.
 31. A process as defined in claim 29 wherein the graft monomer is maleic anhydride.
 32. A process as defined in claim 29 wherein the graft monomer is a derivative of acrylic or methacrylic acid containing 4-16 carbon atoms.
 33. A process as defined in claim 32 wherein the graft monomer is selected from the group consisting of glycidyl methacrylate, methacrylate, methylmethacrylate, ethylmethacrylate and aminopropylmethacrylate.
 34. A process as defined in claim 29 wherein the graft monomer is a vinyl amine containing 2-25 carbon atoms.
 35. A process as defined in claim 34 wherein the vinyl amine is selected from the group consisting of allylamines, N-vinylpyridines, N-vinylpyrrolidones, vinylcarbazoles, vinylimidazole and vinylthiazoles.
 36. A process as defined in claim 29 wherein the graft monomer is selected from the group consisting of vinyl silanes and vinylbenzyl halides.
 37. A process as defined in claim 29 wherein the graft monomer is present in an amount within the range of 0.1 to 6 percent based on the total weight of the polymer.
 38. A process as defined in claim 29 which includes the step of derivatizing the blend with a derivatizing compound containing one or more reactive groups selected from the group consisting of primary amines, hydroxyls and thioles.
 39. A process as defined in claim 38 wherein the derivatizing compound is selected from the group consisting of alkylene polyamines, aryl polyamines, heterocyclic polyamines and combinations thereof.
 40. A process as defined in claim 22 wherein the simultaneous blending and shearing is carried out at a processing temperature within the range of 150° to 350° C.
 41. A process as defined in claim 22 wherein the simultaneous blending and shearing is carried out in a mixer having the capability of effecting mechanical work to reduce the molecular weight and the molecular weight distributions.
 42. A process for producing an ethylenepropylene polymer blend comprising simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, and reacting the polymer blend with a graft monomer to form a functionalized blend, and further reacting the functionalized blend with a reactive organic compound containing one or more reactive groups consisting of primary amines, hydroxyls and thioles to form a derivatized polymer blend, having a number average molecular weight within the range of about 300 to about 5,000.
 43. A process as defined in claim 42 wherein at least one of the low ethylene content ethylene-propylene polymer and the higher ethylene content ethylene-propylene polymer includes a polyene monomer copolymerized therewith containing two or more carbon to carbon double bonds and containing 4-20 carbon atoms.
 44. A process as defined in claim 42 wherein the graft monomer is selected from the group consisting of unsaturated dicarboxylic acid anhydrides and their corresponding acids.
 45. A process as defined in claim 42 wherein the graft monomer is a derivative of acrylic or methacrylic acid containing 4-16 carbon atoms.
 46. A process as defined in claim 42 wherein the reactive organic compound is selected from the group consisting of alkylene polyamines, aryl polyamines, heterocyclic polyamines and combinations thereof.
 47. A process as defined in claim 42 wherein the reactive organic compound is an aryl polyamine selected from the group consisting of N-phenyl-phenylene diamines, N-naphthylphenylene diamines and substituted derivatives thereof.
 48. A process as defined in claim 42 wherein the reactive organic compound is a heterocyclic polyamine selected from the group consisting of aminocarbazoles, aminoindoles, aminopyrroles, amino-indazolinones, aminoperimidines, aminomercaptotriazoles, aminomorpholines, aminopiperazines, aminopiperidines, aminophenothiazines, aminopyridines, aminopyrazines, aminopyrimidines, aminoimidizolidones, aminothiadiazoles, aminothiothiadiazoles, aminobenzotriazoles, aminoimidazoline and aminothiazolines.
 49. A process as defined in claim 42 wherein the derivatizing compound is selected from the group consisting of a mercaptothiazole, and a mercaptobenzoimidazole.
 50. An ethylene-propylene polymer blend having a number average molecular weight within the range of about 1,000 to 12,000 and a molecular weight distribution within the range of about 1.5 to about 5 prepared by the process of simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50.
 51. A derivatized ethylene-propylene polymer blend having a number average molecular weight within the range of about 1,000 to about 12,000 and a molecular weight distribution within the range of about 1.5 to about 5 prepared by the steps of simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, reacting the polymer with a graft monomer to form a functionalized blend, and further reacting the functionalized blend with a reactive organic compound containing one or more reactive groups selected from the group consisting of primary amines, hydroxyls and thiols.
 52. A process for producing an ethylene-propylene polymer blend comprising simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, with the blending and shearing being carried out such that the polymer blend has a number average molecular weight within the range of about 1,000 to about 12,000.
 53. A process for producing an ethylene-propylene polymer blend comprising simultaneously, in the absence of solvent, blending and shearing:(a) an essentially amorphous low ethylene content ethylene-propylene polymer containing an ethylene to propylene mole ratio within the range of 35/65 to 65/35, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7; (b) a partially crystalline higher ethylene content ethylene-propylene polymer containing an ethylene to propylene molar ratio within the range of about 65/35 to about 85/15, having a number average molecular weight within the range of about 20,000 to about 150,000 and a molecular weight distribution within the range of about 2 to 7;whereby the blending and shearing is carried out under conditions of heat and mechanical work sufficient to create high shear conditions for a time sufficient to reduce the molecular weight and molecular weight distribution of the blend of (a) and (b), wherein the weight ratio of low ethylene content ethylene-propylene polymer (a) to the higher ethylene-propylene polymer (b) is within the range of about 80/20 to about 50/50, and reacting the polymer blend with a graft monomer to form a functionalized blend, and further reacting the functionalized blend with a reactive organic compound containing one or more reactive groups consisting of primary amines, hydroxyls and thioles to form a derivatized polymer blend, having a number average molecular weight within the range of about 1,000 to about 12,000. 